1. Field of the Invention
The present invention relates to a table saw and in particular, to a locking mechanism to lock an arbor of the table saw while a blade is added to or removed from the arbor.
2. Scope of the Prior Art
Table saws use rotating blades to cut various substances, most particularly wood. As such, table saws typically include an outer frame portion that has an upper surface on which the wood or other materials can be placed and moved along as it is cut by the blade. The upper resting surface of the table saw has an opening through which the cutting blade passes. Depending upon the size of the opening, the opening can be enclosed with a plate that includes a slot through which the blade passes.
Table saws also include motors that are used to rotate the blade at the necessary speed to cut the wood or other substance. The table saw motor is supported by the frame in any number of known methods. The table saw can also include a bearing plate that is connected proximate the slot to the underside of the upper surface. Thus, the bearing plate is positioned between the motor and the blade.
In order to turn the blade, the motor, rotates an arbor, spindle, output shaft or mandrel. The term arbor will be used to include spindle, output shaft, or mandrel. The arbor has a first end that is connected by the motor. At the second and distal end, the blade of the table saw is removably attached. In those embodiments that include a bearing plate, the bearing plate includes a hole through which the arbor passes. The bearing plate hole is large enough so that the arbor can rotate freely within that hole.
Typically, the blade is held by a nut against a shelf formed on the arbor. In order to secure the blade and the nut to the arbor, a user typically uses two wrenches. The first wrench is used to hold the rotatable arbor in a stationary position, and the second arbor is used to rotate the nut against or away from the blade. Various different methods are used to ensure that the nut is tightened with sufficient torque thereby securing the blade to the arbor for correct use of the table saw.
The use of two wrenches to secure the blade to the arbor can be difficult and awkward. In addition, the method is not conducive to ensure that the nut is tightened to the correct torque because of the counter-balance turning of the two wrenches. Accordingly, it is needed to develop an arbor locking mechanism that can lock the arbor in position while the blade is being secured to the arbor. In addition, the arbor locking mechanism must be easy to use and easy to access through the opening in the upper surface of the frame.
Arbor locking plates are commonly used in other types of power tools such as routers. The use of the arbor locking plates on these tools are different from the present invention because of the size of both the tool and the rotating arbor on the tool. The size of the tool and the arbor make it often necessary for the tool to include a simple arbor lock mechanism to attach a working implement to the arbor. In addition, the design of such routers can make it difficult to reach the arbor lock mechanism thereby requiring the tool's frame or casing to be disassembled to access the arbor locking plate.
Arbor locking plates have also been used on table saws. Such arbor lock plates include a pivot point that attaches the arbor lock plate to the frame of the saw. The arbor lock plate also includes a large slot through which the arbor of the table saw passes. The large slot is on the opposing end of the arbor plate from the pivot point and has a large lower section and a smaller upper section. The arbor can rotate freely through the large lower section and locks the arbor in a stationary position in the smaller upper section. The arbor can be configured with a portion having flat opposing edges and where the flat opposing edges are placed within the slot. In this configuration, the smaller upper portion engages the flat opposing edges of the arbor thereby locking the arbor. Accordingly, a blade can be secured or removed from the arbor.